21135441205 has 4 divisors (see below), whose sum is σ = 25362529452. Its totient is φ = 16908352960.

The previous prime is 21135441161. The next prime is 21135441211. The reversal of 21135441205 is 50214453112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16480654129 + 4654787076 = 128377^2 + 68226^2 .

It is not a de Polignac number, because 21135441205 - 2²¹ = 21133344053 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2113544116 + ... + 2113544125.

It is an arithmetic number, because the mean of its divisors is an integer number (6340632363).

Almost surely, 2^21135441205 is an apocalyptic number.

It is an amenable number.

21135441205 is a deficient number, since it is larger than the sum of its proper divisors (4227088247).

21135441205 is an equidigital number, since it uses as much as digits as its factorization.

21135441205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4227088246.

The product of its (nonzero) digits is 4800, while the sum is 28.

Adding to 21135441205 its reverse (50214453112), we get a palindrome (71349894317).

The spelling of 21135441205 in words is "twenty-one billion, one hundred thirty-five million, four hundred forty-one thousand, two hundred five".